This proposal requests continued support for a virology training program. The faculty is derived from two different entities within the New York University system, the Mount Sinai School of Medicine (MSSM) and the NYU School of Medicine (NYUSM). The program goal remains to assist in the training of graduate and postdoctoral students in the broad discipline of Virology. The research training emphasis is directed toward teaching students the theory and experimental approaches required for independent scientific investigations. Students learn the molecular mechanisms involved in virus replication and host responses to viral infections. Additional research training areas include novel approaches for antiviral strategies and vaccine development. Recent emphasis includes projects relevant to the Biodefense Research Initiative. By combining the strengths of outstanding groups of virologists, we have created a world-class virology training program which is of enormous benefit to the research community in New York City. This program is built upon existing collaborations, including program project grants, subcontracts, and joint publications between faculty members of MSSM and NYUSM. Accordingly, our collaborative training effort has "added value" over single-institution or individually based initiatives. The program faculty consists of twenty-five outstanding virologists who use a diverse array of experimental strategies to study the molecular, cellular, biochemical and immunological interactions of viruses with their hosts. Aggressive recruitment efforts have allowed us to attract trainees of the highest caliber, including underrepresented minorities. Our trainees are highly successful in attaining independent research positions, peer-reviewed publications, and extramural research funding. Accordingly, ten predoctoral and six postdoctoral positions are requested. The specific aims of the program are (i) to recruit and provide rigorous training to high caliber students and Fellows and (ii) to provide an administrative structure which will support and coordinate virology training between two entities (MSSM and NYUSM) of the same university. The continued support of this program will aid trainees in all phases of their development, including understanding scientific method, interpretation of results, presentation of data and conclusions, research ethics, and career guidance.